Congolese troops have fought back against Rwanda-backed rebels who the U.N. says are moving fast into the South Kivu province after seizing the region’s largest city and an international airport

A major offensive by Rwandan-backed M23 rebels in east Democratic Republic of Congo appeared to have stalled on Saturday after the army took back some ground, two civil society sources and a local official said.

The U.N. says Rwanda-backed rebels are expanding their presence in eastern Congo after capturing the region's major city.

There has been fierce fighting as Rwanda-backed M23 rebels advance towards the second-largest city in eastern Democratic Republic of Congo, marking a further escalation in the region's conflict. M23 fighters have been moving south, towards Bukavu, the capital of South Kivu, after capturing the largest city in the region, Goma.

Congolese troops with support from Burundi's army appeared on Friday to be holding back a push south by Rwandan-backed rebels seeking to expand their grip on eastern Congo in a weeks-old advance that has raised fears of a broader regional conflict.

Southern African heads of state re-affirmed their support for Democratic Republic of Congo in its fight against Rwanda-backed rebels who continue to take new territory in the east of the country.